Since 1965 the applicant has been studying the chemical control of maternal behavior in the rat. The present proposal seeks to continue this work, focusing on the regulation of the behavior through changes in pheromonal emission. What has come to be called the "maternal pheromone" was discovered in the Applicant's Laboratory in 1971. Recently we found that the lactating female is not alone in emitting the pheromone. The nulliparous female, when behaving maternally, also emits the pheromone. Herein we propose a series of studies that relates pheromonal emission in both the lactating female and the maternally-behaving nulliparous female to selected events occurring within the liver.